$ svn sw http://svn.automattic.com/wordpress/tags/2.3 U wp-pass.php U wp-rss.php U wp-login.php ... Updated to revision 6166.
More information on the release can be found here: WordPress 2.3. Now you can tag your posts like it’s 2003!
I’m happy to walk anybody through the minutia of getting an svn install of WordPress set up for yourself (assuming you’re already comfortable with sshing to your webhost/server).